Web tensioning and controlling mechanism for printing machines and the like



Sept. 27, 1932. TAYLOR ET AL WEB TENSIONING AND CONTROLLING MECHANISM FOR PRINTING MACHINES AND THE LIKE Filed Aug. 29, 1931 3 Sheets-Sheet 1 fire 775x15 HWwLoR 4 WG/aso/v Sept. 27, H, TAYLOR ET AL 1,879,591

WEB TENSIONING AND CONTROLLING MECHANISM FOR PRINTING MACHINES AND THE LIKE 5 Sheets-Sheet 2 Filed Aug. 29, 1931 p 2- H TAYLOR ET AL' 1,379,591

' WEB TENSIONING AND CONTROLLING MECHANISM FOR PRINTING MACHINES AND THE LIKE Filed Aug. 29. 1931 3 Sheets-Sheet 5 Patented Sept. 27, 1932 untrue sraras PATENT orrlcs HENRY TAYLOR AND WILLIAM GIBSON,

OF NEWCASTLE-ON-TYNE, ENGLAND, AS-

SIGNOILS TO J. H. HOLMES 8a COMPANY LIMITED, OF HEBBURN-ON-TYNE, ENGLAND, ABEGZELEREDCOMPANY F GREAT BRITAIN WEB TENSIONING AND CONTROLLING MECHANISM FOR PRINTING MACHINES AND THE LIKE Application filed August 2a, 1931, Serial no. 580,180, andin Great Britain October 22, 1930.

This invention relates to web tensioning and controlling mechanism for printing ma chines and the like.

It is well known that the controlling of the rate at which the paper or web is supplied to a printing machine is very important and is also difiicult on account of the mass of the roll, its varying diameter and the speed at which the web has to pass to the machine. Various arrangements of braking bands or aprons have been suggested, in some of which one end of the apron has been secured to a fined point through springs and the other end attached to a drum capable of rotation to vary the pull or tension on the apron.

The present invention relates to web tensioning and controlling mechanism of this general type.

According to this invention the apron drum, i. e. the drum to which one end of the apron or series of bands is attached, is coupled to its spindle through a spring,the spindle being rotated to vary the stress in the spring coupling and thus regulate the pull or tension on the apron. Y

The rotation of the spindle is preferably cii'ected by an electricmotor which may be manually controlled or automatically controlled in accordance with the tension of the web passing to the printing machine. The

motor may be geared to the spindle by worm or other gearing which is preferably irreversible, i. e. although the motor can drive the spindle in either direction it cannot be driven from the spindle.

Normally the tension on the apron is vas ried through the spring coupling but in order that, when desired, as for instance when the pr ting machine is stopped quickl the braking action of the apron on the web roll may he suddenly increased, mechanism is con. veniently provided whereby the apron drum can be rotated independently of the spring coupling. This mechanism may be in the form of a pivoted catch lever or like device a tuated, say,by a solenoid and is preferably so interlocked with switches controlling the main driving motor of the printing press th it is automatically brought intooperation when the press is stopped.

-when the position of the device corresponds to the position of the controller whereby the position of the controller affords a direct indication of the web tension. Preferably the device controlled'by the Web tension comprises a follow-up controller driven by the motor or by the drum spindle and adapted to open the circuit of the motor when the web tension corresponds to the setting of the hand-operated controller.

Each controller may be provided with a series of contacts, corresponding contacts of the two controllers being connected together. The follow-up controller then hasadriven contact device so formed that it engages all but one of the contacts of the controller, the motor circuit being so connected to the two controllers that the motor is inoperative when the disengaged contact of the follow-up controller corresponds to the contact engaged by the handle on the hand-operated controller.

In another convenient system the motor is controlled by two switches, preferably of the push-button type, the two switches being arranged so to control the motor that when one switch is closed the motor rotates in one direction to increase the web tension whilst when the other switch is closed the motor rotates in the other direction to reduce the Web tension. Conveniently the motor is provided with two oppositely wound field circuits, preferably connected in series with the motor armature, and the control switches are arranged so that the circuits of the armature and one field are completed by the operation of one switch and the circuits of the armature and the other field by the operation of the other switch.

In the case of a printing machine having a normal .speed and a slow speed (for starting, making joins in the paper and other purposes) obtained by driving the machine respectively by a main motor and by an auxiliary motor, the switches controlling the selec tion of the speed may be provided with auxiliary contacts which are so associated with thecontrol system of the tension motor that the web tension is reduced automatically to a predetermined value during slow speed running of the machine.

Thus when the control system having the hand-operated and follow-up controllers is employed, the auxiliary contacts are arranged so that during slow speed running of the machine the controller handle is rendered ineffective and the contacts of the controllers corresponding to the appropriate value of web tension are rendered operative to control the tension motor. \Vhen the push-button control system is employed the auxiliary contacts are arranged so that the motor operates automatically to reduce the web tension during the change from normal to slow speed and to restore it to the normal value during the change from slow to normal speed, limit switches operated by the drum spindle or the motor preferably being provided to open the motor circuit when the web tension reaches the appropriate value.

The following is a description, by way of example, of one construction of web tensioning and controlling mechanism and of two forms of control arrangement therefor, according to this invention, with reference to the accompanying drawings, in which,

Figure 1 shows, diagrammatically, the general arrangement of a printing machine, its driving and control gear, and its web tensionin g mechanism,

Figure 2 is a sectional side elevation of the web tensioning mechanism on an enlarged scale,

Figure 3 is an end elevation of the web tensioning mechanism shown in Figure 2,

Figure 4 is a wiring diagram of the preferred form of control arrangement,

Figure 5 is a sectional side elevation of a follow-up controller for use in the control arrangement shown in Figure 4,

Figure 6 is a wiring diagram of another form of control arrangement, and

Figure 7 shows, in side elevation, a detailed view of switches employed in the control arrangement of Figure 6.

As shown in Figure 1 a printing machine X having rollers X is positivelycoupled to a countershaft X directly connected to a main motor X and also connected through an overrunning clutch X to an auxiliary motor X During normal operation the machine is driven by the main motor X whilst the auxiliary motor X is used for starting and for slow speed running such as is required when, for example, a join is being made between the paper from a new web roll and that from the old roll which is almost emptied.

The motor X is energized from supply mains Y Y through a main switch Y and starting control gear, indicated by the square Y of any suitable kind, the control gear Y being provided with an auxiliary contact P which is closed when the control gear is in the off or start position, and which is associated with the control apparatus for the web tensioning mechanism in a manner to be more fully described hereinafter. The motor X is also energized from the mains Y Y through a switch Y and control gear Y. The switches Y and Y are respectively provided with auxiliary contacts P and P the contact P being closed when its associated switch is open and the contact P being closed when its switch is closed. These auxiliary contacts are associated with the control arrangement (indicated by the square 1)) of the web tensioning mechanism.

The web Z for the machine X is supplied from a web roll Z mounted in bearings on arms Z forming part of a supporting frame (not shown) of any suitable form. The web Z passes from the roll over a guide roller Z to the rollers X of the machine. The tension of the web is controlled by a braking apron, or a series of bands, A which engages the periphery of the web roll Z and has one end connected by one or more adjustable springs A to a fixed point A and the other end attached to an apron drum A. The drum A is controlled, in a manner to be more fully described, by a tension motor D to vary the pull or tension on the apron A which acts in the well known manner to exert a braking effort on the web roll Z and thus to vary the web tension.

Referring now to the more detailed views of the web tensioning mechanism shown in Figures 2 and 3, the apron drum A is mounted on bearings A A on a spindle B which can be rotated. The drum A is connected to the spindle B by means of a helical spring G which encircles the spindle inside the drum and has one of its ends attached to an internal flange A on the bearing A and the other end to a collar B keyed to the spindle B, there being sufiicient space between the turns of the spring C to allow for an increase in the number of those turns when the spring is tightened by the rotation of the spindle.

When the spindle B is rotated the spring C is stressed and thus tends to rotate the drum A so that the pull or tension on the apron A depends upon the amount the spring is stressed by the rotation of the spindle. The spindle is driven by a small electric motor D through a worm gearing D D which permits the motor to drive the spindle in either direction but prevents the motor being driven by. the spindle. vThemotor can be controlled in any convenient manner .so as to adjust the tension on the apron to maintain the Web tension at the correct value, butit is preferably controlled by one or other "of the arrangements described in detail hereinafter.

In order thatithe tension on the apron may he suddenly increased, as for instance when the machine is stopped quickly, the end of the drum A, in which the hearing A is mounted, is provided with a pulley-like flange A having an external friction surface A adapted to'be engaged by a cam nose E on a lever E which is pivoted to a lever E car ried freely on the spindle B. The lever E is normally maintained in its inoperative position, in which the nose E is disengaged from the surface A, by a spring F (Figure 3) which'holds the. levers E and E. against a fixed stop F The lever E is moved into its operative position by a solenoid F the plunger of which is connected. to the lever E by a pivoted link F and which, when ener gized, acts in the opposite direction to the spring F. v

i i hen the solenoid F is energized the end of the lever E is pulled in the direction of.

the arrow G as indicated in Figure ,8, so that it turns about its pivot and presses the nose E the friction surface A. This has the effect of locking the levers E and'E together so that they form, in effect, a rigid member, and the continued pull of the solenoid F 2 acting on this rigid member rotates the drum A in the direction of the arrow G positively and independently of the spring C. When the solenoid F is deenergized the spring F moves the two levers in the opposite direction to the arrow G so that the lever E engages the stop F andthen the lever E turns about its pivot suflicientlyto cause the cam nose E to disengage the surface A before this lever also engages the stop.

The solenoid may be controlled in any convenient manner but ispreferably, as in the control arrangements to be described, so interlocked with the switch or circuit-breaker controlling the main motor driving the print- C 77 mg press, or with the stop control devlce of the main motor, that it is automatically operated when the circuit of, the motor is opened. v

In the preferred form of control arrangement indicated by the square D in Figure 1 and shown diagrammatically in Figure 4' the armature D of the tension motor D is connected on one side to the mid'wire H of a three-wire direct current supply circuit having positive and negative outer wires H and H respectively. The shunt field D of the motor is permanently connected to the mid-wire H and the positive outer H The other side of the armature D of the the relay is in its deenergized position, to

the handle K of a face-plate controller having a number of contacts,K K arranged so that the handle, can be rotated to engage any one contact. In order to. ensure that the handle K may always rest directly on a contact and cannot remain in an intermediate position between two contacts, an oted on the frame of the controlleris provided with a spring L arranged so that a roller L? on the end of the arm is pressed between the teeth of a star wheel L carried by the controller handle K.

The contacts K -K are connected through a multi-core cable I '--indicated in dotted lines to the corresponding contacts M M of a. controller, hereinafter referred to as the follow-up controller, which is provided with a rotatable disc M corresponding to the handle K. 'The follow-up controller is mounted on a bracket X on the printing machine X adjacent the tension motor D whilst the hand-operated controller can be; arranged at any suitable remote point.- The disc M of the follow-up controller is of insulating material and is provided with two circumferential conducting segments N, N which are sufliciently long to engage all but one of the contacts ously, the segments being separated from one another by insulating strips N and N 3 having a width slightly greater than that of. one contact. The segment N is connected to the positive outer H of the supply circuit and the segment N The disc M is mechanically connected to the tension motor by a chain N and suitable reduction gearing.

In the preferred form of follow-up controller shownin F igure 5 the-segments N, N 1 are arranged on the circumference of the disc M so that they jecting from a fixed disc Oof insulating material mounted behind the disc M. The disc M is rigidly mounted on a shaft 0 which is driven through reduction gearing 0 O and O by the controller being mounted in a casing 0 r In describing the operation of the control arrangement it will be assumedthat when the motor armature D is connected to the positive outer H it rotates the spindle B in the direction of arrow G in Figure 3 and thus tightens the spring C and increases the web tension, whilst when it is connected to thenegative outer H it rotates to decrease-the web tension.

' The setting of the controllers is arranged so that during normal operation a suitable value of web tension is obtained when the handle K is on, say, the centre contact K the gearing O O 0 and the chain N being arm L piv M M simultanes.

to the negative outer H are engaged by spring, contacts, one of which is shown at M prochain N, the whole direction, say to the'next contact K so that a circuit is completed for the motor from the handle K, its contact K the contact M of the follow-up controllerand the segment N to the positive outer The motor now rotates the spindle B to increase the web tension and, at the same time, drives the disc M in a clockwise direction until the contact M leaves the segment N and engages the strip N". The motor circuit is then opened and the motor stops, the web tension remaining constant at the new value.

Further movements of the handle K in a counter-clockwise direction cause further increases in web tension, the motor being stopped after each movement of the handle as soon as the insulating strip N engages the corresponding contact of the follow-up controller. If the handle K is moved in a clockwise direction, say from the position shown to the contact K, the circuit of-the motor is completed through the contact M and the segment N to the negative outer H2. The motor accordingly rotates the spindle B to decrease the web tension, the'disc M rotating in a counter-clockwise direction until the contact M engages the strip N and the motor stops.

The tension of the apron depends directly on the tensioning of the spring which in turn varies, within normal limits, with the number of turns of the spindle. Hence it will be apparent that since the disc M has a definite position corresponding to each position of the motor D and the spindle B, that is to each value of web tension, and that since this position corresponds to the position of the handle K, the position of this handle provides a visual indication of the value of the web tension. Thus the contacts K K can, if desired, be calibrated to indicate in pounds, or other suitable units, the value of web tension for each position so that the handle can be set by an operator to give any desired value of web tension.

It is usually found desirable in practice to reduce the web tension while a oin is being made between the paper from a new reel and that from the old reel which is almost emptied. Such joins are made when the press is running slowly, this slow running being obtained by switching off the main motor X and driving the press from the auxiliary motor X.

The web tension can obviously be adjusted to the desired reduced value when the speed of the machine is reduced prior to makinga 10m and restored to normal value as soon as the speed of the machine 1s increased again,

by moving the handle of the controller to the appropriate contact.

' It is, however, desirable that these changes before and after the join is made, should be automatic. Accordingly an additional connection is provided between the armature D connection including a contact J 2 of the relay J which is closed when the relay is in its energized position. The circuit of the relay J is controlled by the auxiliary contact P on the main motor switch Y (Figure 1) and the auxiliary contact P on the auxiliary motor I switch Y Thus when the auxiliary motor is brought into operation and the main motor switch opened prior to making a join, the contacts P and P are closed to complete the energizing circuit of the relay J which accordingly operates to open the contact J and to close the contact J The circuit of the armature D of the tension motor through the handle K is thus opened at the relay contact J and the handle K is rendered inoperative. The armature D is however connected through the relay contact J 2 to the contact M of the follow-up controller and thence through the segment N to the negative outer H so that the motor rotates to reduce the web tension until the disc M is moved to the position in which the strip N engages the controller contact M As soon as the join has been made the main motor switch Y is again closed, thus opening the auxiliary contact P and deenergizing the relay J. The armature D is disconnected from the controller contact M and connected to the handle K by the opening and'closing of the relay contacts J z and J respectively. The tension motor is thus connected to the positive outer H and rotates to restore the web tension to its normal operating value as determined by the position of the handle K.

The solenoid F for increasing the tension on the apron for braking purposes is controlled by the main control circuit of the machine so that it is energized when the stop push-button of the machine is operated.

Thus a stop relay R is normally energized from the supply circuit H, H through a holding circuit including a contact R of the relay, which is closed when the relay is energized, and a stop push-button R The relay R is provided with additional contacts R and R which are respectively closed and open when the relay is energized. The contact R controls the circuit of a holding coil Y for the switch Y so that this switch is held in its closed position, the circuit of the coil Y being opened to allow the switch to open and stop the machine whenthe relay R is deenergized. The contact'R acts to complete the circuit of the solenoid F when the relay is deenergized.

hen the push-button R is depressed the holding circuit of the relay R is opened so that this relay deenergizes to open the con tact R to stop the machine, and to close the contact R to energize the solenoid F to increase the web tension for braking in the manner described above. When the machine stops, its main control gear Y (Figure 1) is returned to the start position in which the auxiliary contact P is closed, this contact completing a pick-up circuit for the relay B so that, provided the button R has been released, this relay is energized and operates to open the circuit of the solenoid F at the contact R to complete its own holding circuit at the contact R and to close the circuit of the holding coil Y at the contact B so that the machine can be restarted when desired. i

It will be noted that when the main motor is stopped and the auxiliarymotor started for making a join, the push-button R can be used to stop the main motor and the solenoid F will act to increase the web tension during slowing up of the machine irrespective of the position of the spindle B and the movements of the motor to decrease the web tension, the solenoid F 2 being deenergized as soon as the main motor stops so that the web tension resumes the appropriate value for slow speed running. as determined by the follow-up controller in the manner described above.

In the alternative control arrangement shown in Figure 6 a tension motor D is em ployed having an armature D and two oppositely wound series field coils D D one or other of which is operative when the motor rotates to vary the web tension. In the following description it will be assumed th at when the motor armature D is connected to the direct current supply circuit H H in series with the field coil D the motor rotates the spindle B in the direction of the arrow G (Figure 3) to increase the web tension, i

whilst when the field coil D" is used the motor rotates in the opposite direction to decrease the web tension.

One side of the armature D is connected to the supply conductor H and the other side to one end of each field coil. The other end of the field coil D is connected to the other supply conductor H in series with a limit'switch S, which is operated by the spindle B ina manner to be more fullydescribed to prevent the web tension being increased beyond a predetermined value, and an increase pushbutton switch T. The other end of the field coil D is connected to the supply conductor H in series with a limit switch S which prevents the web tension being reduced below a predetermined value, button switch T Thus the push-buttons T and T, which can be arranged at any suitable remote point, when operated respectively cause the motor to rotate to increase the web tension and to decrease the web tension, the maximum value of the web tension being controlled by the setting of the limit switch S and the minimum value by the setting of the limit switch S The limit switches S S may be operated in any desired manner to prevent the motor D rotating the spindle B too far in either di rection from anormal position but these switches are preferably constructed and arranged as shown infFigure 7 so that they are operated by a nut which travels on a screwthre'aded portion of the spindle B. As shown in this figure the spindle B, is provided with a screwthreaded'portion B at one end for a nut B which engages a fixed guide (not shown) arranged so as to prevent the nut from rotating but to permit itto travel along the screwthreaded portion B as the spindle B is rotated. The screwthreaded portion B may bedisposed at either end of the spindle B but is preferably at the end adjacent the worm wheel D as indicated in dotted lines in Figure 2. The switches S and S are carried on an lnsulating support U, arranged below the screwthreaded portion B each switch con slstlng of a pivoted arm U which is normally held in engagement with a contact stud U by a spring U but which is rocked about its pivot to disengage the stud when an upward 1y projecting lug U on the arm U is engaged y a pin B on the nut 13 as this nut travels along the'screwthreaded portion B When the motor rotates the spindle in the direction of the arrow G (Figure 3) to increase the web tension the nut travels along the screwthreaded portion B towards the switch S and, if the push-button T is held closed, the motor continues to rotate until the pin 13* engages the lug U of theswitch S, thus opening this switch and stopping the motor. r

Theweb tension remains at the maximum and a reduce pushvalue, as determined by the position of switch S, until the push-button T is depressed to cause the motor to rotate in the opposite di rection, the web tension being reduced to its minimum value if the button T is held closed until the pin B engages the lug U of switch S It'will be appreciated that the initial position of the nut B on the screwed spindle and the switches S and S can be arranged so that the maximum and minimum values of web tension are fixed at any desired amount. 1 p

As in thearrangement shown in Figure 4, auxiliary circuits can be provided for causing the web tension to be reduced automatically when the machine is driven at slow speed by the auxiliary motor and to be increased again as soon as the normal running conditions are resumed.

This automatic control is effected by two relays V and W and two limit switches S and S operated by the nut B in a similar way to the switches S and S The relay V is controlled by the auxiliary contact P on the HMiIiIHOtOI switch Y which is open when the contactor is closed so that under normal running conditions, with the main motor driving the machine, the relay V is in its deenergized position. The relay V is controlled by the auxiliary contact P on the auxiliary motor switch Y which is open when the contactor is open so that under normal running conditions this relay is also in its deenergized position. The relay V is provided with contacts V and V which are re- 7 spectively closed and open when the relay is deenergized and the relay V with contacts and both of which are open when the relay is deenergized.

The limit switches S and S may be mounted on the insulating'support U (Figure 7) on the opposite side of the spindle to the switches S and S so that they are actuated by a .pin, similar to the pin 13, on the opposite side of the nut B The switch S is arranged so that it is opened by the pin when the web tension is at its normal operating value whilst the switch S is arranged to be opened when the web tension is reduced to the appropriate value for slow speed running.

The auxiliary circuits consist of a shunt or bridging circuit for the increase pushbutton T which connects the end of the motor field coil 1) to the supply conductor H through the limit switches S and S and the contacts V and V of the relays V and W respectively, and of a shunt circuit for the reduce push-button T which connects the end of the motor field coil D to the conductor H through the limit switches S and S and a the relay contacts V and W these shunt circuits being operative during the transition period to short-circuit one or other of the push-buttons and complete the circuit of the motor through one or other of the field coils so that it rotates in the appropriate direction.

During normal operation the main motor switch Y is closed and the auxiliary motor switch Y open so that relays V and W are deenergized and. the shunt circuit for the push-button T is open at the limit switch S and relay contact W whilst the shunt circuit for the push-button T is open at the relay contacts V and Vi. The web tension can thus be controlled by the push-buttons.

lVhen a join is to be made the auxiliary motor switch Y is closed (before the main motor switch Y is open to ensure a smooth transference of drive) thus completing at the contact P the energizing circuit of the relay which operates to close its contacts W W. No change in web tension takes place, how ever, as the shunt circuit of the push-button T is open at thelimit switch S The main motor switch is then opened, thus shutting down the main motor X and completing at the contactP the circuit of the relay V which operates to open its contact V and close its contact V thus completing the shunt circuit of the push-button T The motor D then rotates to decrease the web tension until, when it reaches the appropriate value, the limit switch S opens and the motor is stopped.

As soon as the join has been made, the main motor switch Y is again closed thus deenergizing the relay V which acts to open its contact V and to close, at its contact V the shunt circuit of the push-button T. The motor D then rotates to increase the web tension until, when it reaches the normal operating value, the limit switch S opens. The auxiliary motor switch Y is then opened to allow the motor X to come to rest and to deenergize relay W which at its contacts WW and Vi opens further points in the two shunt circuits so that complete control of the web tension is obtained by the push-buttons independently of the limit switches in their bridging circuits.

As in the arrangement shown in Figure 4:, the solenoid F for suddenly increasing the web tension when the machine is stopped is controlled by a normally energized stop relay R. If desired, however, this solenoid may be controlled by additional contacts on the relays V and V arranged so that the solenoid is energized when the relay V is energized and the relay W deenergized, that is, when both the main motor and auxiliary Inotor switches are open.

It will be appreciated that the above description is by way of example and that various modifications may be made both in the constructional details of the drum and spindle and also in the control arrangements within the scope of the invention.

Thus, for example, the helical spring between the spindle and the drum may be a closely wound helix with its turns practically touching, in which case the collar by means of which one end of the spring is connected to the spindle may be keyed to but'slidable along the spindle so as to allow for the necessary end movement of the spring when the spindle is rotated. Again, the mechanism for producing the sudden increase in the tension of the apron during stopping of the machine may be so constructed that when put into operation it acts as a rigid connection between the spindle and the drum, the drum being then directly driven by the motor which usually drives it through the spring coupling.

Vhen the machine is driven by a two-speed motor instead of a duplex motor equipment iii consisting of a main and an auxiliary motor, the auxiliary contacts which, in the control arrangements described, act to cause the automatic change in web tension during the change in speed of the motor are arranged in the appropriate manner on the change speed switch or switchesof the motor.

In the control arrangement employing the hand-operated and follow-up controller the.

follow-up controller may be provided with a rotating member having the segments on the face instead of the periphery thereof and the cooperating contacts suitably modified, whilst in the puslrbutton control arrangement a tension motor may be employed which has a single field winding and two independent armatures or armature windings arranged so that when one armature winding is energized the motor rotates in one direction and when the other armature winding is energized the motor rotates in the other direction.

It will also be understood that either control arrangement may have the handbperated control device, i. e. the controller handle or push-buttons, as the case may be, supplemented by a device which operates to control the motor automatically in accordance with the web tension. Such an automatic control device may consist of a spring-controlled guide or tension roller, over which the web passes on its way to the printing machine, this roller beingarranged to operate the control handle or push button's through some form of clutch or like coupling which will permit the motor to be controlled manually,

independently of the automatic control, when desired.

What we claim as our invention and desire to secure by Letters Patent is 1. F or use with a printing machine having a main driving motor the combination with a stop switch for the motor of webtensioning and controlling mechanism comprising a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached,a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor and means for rotat ing the drum independently of the spring coupling to increase the tension on the apron suddenly, such means comprising a pivoted catch lever acting directly on the drum, an

5 operating solenoid therefor and neans tor energizing the solenoid controlled by the stop switch whereby the solenoid is energized to actuate the lever when the switch is operated to stop the main driving motor.

2. W'eb-tensioning and controlling mechanism for printing and like machines comprising, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is at tached, a spindle for the drum, a spring for couplingthe drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor and limit switches operated by. the spindle for rendering the said energizing means ineffectached-atone end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motoroperatively connected to the spindle, a source of supply for the motor, a hand-operated controller for the motor and a device controlled in accordance with the apron tension, the arrangement being such that the device acts to disconnect the motor from the source of supply when the position thereof corresponds to the position of the controller whereby the position of the controller affords a direct indication of the apron tension.

4. Vieb-tensioning and controlling mechae nism for printing and like machines comprising, in combination, a braking apron attached at one end to afifixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle,'an d means for energizing the motor including a hand-operated controller and a follow-up controller driven by the spindle, the arrangement of the controllers being such that the follow-up controller disconnects the motor from the energizing means when the apron tension corresponds to the setting of the hand-operated controller.

5. lVeb-tensioning and controlling mecha nism for printing and like machines comprising, in combination, a braking apron at-,

tached at one end to a-fiXed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, a source of supply for the motor, a handoperated controller for the motor, a series of contacts thereon, a handle on the controller 7 adapted in each position to engage one of such contacts, a follow-up controller, a series of contacts thereon, connections between corresponding contacts of the two controllers, a contact device on the follow-up controller driven by the spindle and adapted in each position to engage all but one of the contacts of said follow-up controller, and means for connecting the motor to the supply source and the controllers whereby the motor is inoperative when the disengaged contact of the follow-up controller corresponds to the either direction from its contact engaged by the handle of the handoperated controller. V

6. For use with a printing or like machine having a normal and a slow speed, a webtens'ioning and controlling mechanism comprising in combination a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor, a hand-operated controller for the motor, a follow-up controller driven by the spindle, the arrangement of the controllers being such that the followup controller disconnects the motor from the energizing means when the apron tension corresponds to the setting of the hand-operated controller, and means whereby the electric motor is automatically connected to the energizing means to decrease the apron tension to a predetermined reduced value during a chan e in speed of the printing machine from normal to slow speed. 7

7. For use with a printing or like machine having a normal and a slow speed the combination with control switches for selecting the speed of the machine, of web-tensioning and controlling mechanism comprising a braking apron attached at one end to a fired point, a. drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle,

- an electric motor operatively connected to the spindle, means for energizing the motor a hand-operated controller for the motor, a series of contacts thereon, a handle on the controller adapted in each position to -en gage one of such contacts, a follow-up controller, a series of contacts thereon, connections between corresponding contacts of the two controllers, a contact device on the follow-up controller driven by the spindle and adapted in each position to engage all but one of the contacts of said controlleigauxiliary contacts on the control switches for selecting the speed of the machine, and means for connecting the motor, the controllers, the auxiliary contacts and the energizing means whereby the motor is inoperative when the disengaged contact of the follow-up controller corresponds to the contact engaged by the handle on the hand-operated controller, and when the auxiliary contacts are actuated by the operation of the control switches to change the speed of the machine the motor is connected to the energizing means through the appropriate contacts of the controllers independently of the handle or the driven contact device so that the motor operates automatically during such change in speed to decrease or increase the apron tension according as the speed of the machine is respectively changed from normal to slow speed or from slow speed to normal speed.

8. VVeb-tensioning and controlling mechanism for printing and like machines comprising, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the'apron is attached, a. spindle for the drum, a spring for coupling the drum tothe spindle, an electric motor operatively connected to the spindle, means for energizing the motor, a hand-operated controller for the motor, a follow-up controller driven by the spindle, the arrangement of the controllers being such that the follow-up controller disconnects the motor from the energizing means when the apron tension corresponds to the setting of the hand-operated controller, and means for rotating the drum independently of the spring coupling to increase the tension on the apron suddenly. I

9. For use with a. printing or like machine having a normal and a slow speed, web-tensioning and controlling mechanism comprising, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor, a hand-operated controller for the motor, a follow-up controller driven by the spindle, the arrangement of the controllers being such that the follow-up controller disconnects the motor from the energizing means when the apron tension corresponds to the setting of the hand operated controller, means whereby the motor is connected to the energizing means to decrease the apron tension to a predetermined reduced value during a change in speed of the printing machine from normal to slow speed and means for rotating the drum independently of the spring coupling to increase the tension on the apron suddenly.

1Q. For use with a printing or like machine hav ng a normal and a slow speed, web-tensionlng and controlling mechanism comprismg, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor, two switches for controlling the motor, the arrangement being such that when one switch is operated the m0- tor rotates in one direction to increase the apron tension whilst when the other switch is operated the motor rotates in the other direction to decrease the apron tension and means whereby the motor is automatically connected to the energizing means independently of the switches so that it: rotates to decrease the apron tension to a predetermined reduced value during a change in speed of the printing machine from normal toslow speed and to restore the apron tension to the normal value during a change from slow to normal speed.

11. For use with aprinting or like machine having a normal and a slow speed the combination with control switches for selecting the speed of the machine of web-tensionin and controlling mechanism comprising, a raking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle and having an armature and two oppositely wound field circuits, a source of supply for said motor, two push-button switches for controlling the motor respectively arranged to connect the armature of the motor to the source of supply in series with one or other of the two field circuits, auxiliary contacts on the control switches, and means controlled by said auxiliary contacts for connecting the motor armature to the source of supply in series with the appropriate field circuit and independently of the push-button switches to cause the apron tension to be decreased during a change in the speed of the printing machine from normal to slow speed and to be increased during a change from slow to normal speed.

12. For use with a printing or like machine having a normal and a slow speed, web-tensionin and controlling mechanism comprising, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, an electric motor operatively connected to the spindle, means for energizing the motor, two switches for controlling the motor, the arrangement being such that when one switch is operated the motor rotates inone direction to increase the apron tension whilst when the other switch is operated the motor rotates in the'other direction to increase the apron tension, means whereby the motor is automatically connected to the energizing means independently of the switches so that it rotates to decrease the apron tension to a predetermined reduced value during a change in speed of the printing machine from normal to slow speed and to restore the apron tension to the normal value during a change from slow to normal speed, and limit switches operated by the drum spindle and arranged to disconnect the motor from the source of supply when the apron tension attains a predetermined value as a result of the automatic operation of the motor during a change in speed of the machine.

13. IForuse with a rinting or like machine having a normal an a slow speed the combination with control switches for selecting the speed of the machine, of Web-tensioning and controlling mechanism, comprisin a braking apron attachedat one end to a xed point, adrumtowhich the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum tothe spindle, an electric motor operatively connected to the spindle and having an armature and two oppositelywound field circuits, a source of supply for said motor, two push-button switches for controlling the motor respectively arranged to connect the armature of the motor to the source of supply in series with one or other of the two field circuits, auxiliary contacts on the control switches, means controlled by said auxiliary contacts for connecting the motor armatureto the source of supply in series with the appropriate field circuit and independently of the push-button switches to cause the apron tension to be decreased during a change in the speed oft-he printing machine from normal to slow speed and to be increased during a change from slow to nor-- mal speed, and limit switches operated by thedrum spindle and arranged to disconnect the motor from the source of supply when the apron tensionattains a predetermined value as a result ofthe automatic operation of the motor during a change 1n speed of the ma chine. V V

14. Web-tensioning and controlling mechanism for printing and like machines com prising, in combination, a braking apron attached at one end to a fixed point, a drum to which the other end of the apron is attached,

an electric motor, means for connecting the motor to the drum, a source of supply for said motor, a hand-operated controller for the motor, a follow-up controller driven by the motor, and means for connecting the mo-' tor to the source of supply in series with the controllers whereby'the follow-up controller acts to render the motor inoperative when the two controllers are'in corresponding positions.

15. Web-tensioning and controlling mechanism for printing and like machines comprising, in combination, a breaking apron attached at one end to 'a fixed point, a drum to which the other end of the apron is attached,

an electric motor, means :for connecting the motor to the drum, a sourceot supply for said, motor, a. hand-operated controller for the motor, a follow-up controller driven by the motor, means for connecting the motor to the source of supply in serieswith the controllers whereby the follow-up I controller acts to render the motor inoperative whenthe two controllers are in corresponding posltlons,

and means for increasing the apron tension.

suddenly independently of the motor.

16. Web-tensioning and controlling mechanism for printing and like machines come prising, in combination, a braking apron means including an electric motor for varyingthe tension of the apron, a sourceof supply for said motor, and a control system for the motor comprising a hand-operated controller for the motor, a series of contacts thereon, a handle on the controller adapted in each position to engage one of such contacts, a follow-up controller, a series of contacts thereon, connections between corresponding contacts of the two controllers, a contact device on the follow-up controller driven by the motor and adapted in each po sition to engage all but one of the contacts of said follow-up controller, and means for connecting the motor to the supply source and the controllers whereby the motor is inoperative when the disengaged contact of the follow-up controller corresponds to the contact engaged by the handle of the hand-operated controller.

17. In a printing or like machine the com bination of a main motor for driving the machine at normal speed, an auxiliary motor for driving the machine at slow speed, a source of supply for said motors,a main switch for connecting the main motor to the source of supply, an auxiliary switch for connecting the auxiliary motor to the source of supply, auxiliary contacts on each of said switches, a braking apron for the machine attached at one end to a fixed point, a drum to which the other end of the apron is attached, a spindle for the drum, a spring for coupling the drum to the spindle, a tensioni-ng motor operatively connected to spindle, a source of supply for said motor, a hand-operated controller for 1 the motor, a series of contacts thereon, a

handle on the controller adapted in each position to engage one of such contacts, a followup controller, a series of contacts thereon,

' connections between corresponding contacts sixof the two controllers, a contact device on the follow-up controller driven by the spindle and adapted in each position. to engage all but oneo f the contacts of said controller, means for connecting the tensioning motor, the controllers, the auxiliary contacts and the source of supply .for the tensioning motor, whereby the motor is inoperative when the disengaged contact ofthe follow-up controller corresponds to the contact engaged by the handle on the hand-operated controller and, when the main switch is opened and the auxiliary switch is closed'to change the speed of the machine from normal to slow-speed, the auxiliary contacts on the switches are actu- 1 ated to cause the motor to operate independ ently of the controllers to reduce the web tension to a predetermined value, and means for rotating the spindle independently of the spring coupling to increase the tension of the apron arranged so that it is brought into operation. when the main switch is opened to HENRY TAYLOR.

WILLIAM GIBSON. 

